Machine for high-frequency determinations of wall thickness of bottles and the like



1951 T. c. BAKER MACHINE FOR HIGH-FREQUENCY DETERMINATIONS OF WALLTHICKNESS OF BOTTLES AND THE LIKE 6 Sheets-Sheet l Flled Oct. 17. 1946INVENTOR Tl-ECDCRE C. BAKER BY mviio ATTORNEYS 1'. c. BAKER Nov. 6, 1951THICKNESS OF BOTTLES AND THE LIKE 6 Sheets-Sheet 2 Filed Oct. 17. 1946 79 i I Z n ..I.| I I I I I l I 6 u O 4 O E z I I I z a a a w 7 w I w, HIW W 6 fiH I U fiI HHHIu n I lflnuu 3 l 3 9 vi 6 w 7 b w a 3 M "a 3 2 73 III I w 4 6 l l a 5 4, 3 8 4 5 3 1 I q Hill. "w 7 w 3 u m W 3 x I 7 GG w. a 4 W W m Il I I INVENTOR TI-EODORE c. BAKER ATTORNEYS Nov. 6, 1951'r. c. BAKER 2,573,824

MACHINE FOR HIGH-FREQUENCY DETERMINATIONS 0F WALL THICKNESS OF BOTTLESAND THE LIKE Filed Oct. 17. 1946 6 Sheets-Sheet 3 INVENTOR THEODORE C.BAKER BY 6 E,

ATTORNEYS Nov. 6, 1951 T. c. BAKER 2,573,324

MACHINE FOR HIGH-FREQUENCY DETERMINATIONS 0F WALL THICKNESS OF BOTTLESAND THE LIKE Filed Oct. 17,1946 6 Sheets-Sheet 4 INVENTOR THEODORE C.BAKER ATTORNEYS Nov. 6, 1951 MACHINE FOR T. C. HIGH-FREQUE KNESS OFBOTTLE THIC 6 Sheets-Sheet 5 Filed Oct. 17. 1946 k\\\\\\\\\\\\\k\\\\\\\\\\\\\\ &\\\\\\\\\\\\\\\\\\\\\ TILIEODORE c. BAKER BY 7 $7 R mw. mm. r 5 l & my. E P W M w f .Il l n? L. 1mm h, a

ATTORNEYS Nov. 6, 1951 T. c. BAKER 2,573,824

. MACHINE FOR HIGH-FREQUENCY DETERMINATIONS 01-" WALL THICKNESS OFBOTTLES AND THE LIKE Filed Oct. 17. 1946 e Sheets-Sheetfi ATTORNEYSPatented Nov. 6, 1951 MACHINE FOR HIGH-FREQUENCY DETER- MINATIONS OFWALL THICKNESS OF BOTTLES AND THE LIKE Theodore C. Baker, Perrysburg,Ohio, assignor to Emhart Manufacturing Company, a corporation ofDelaware Application October 17, 1946, Serial No. 703,726

6 Claims. (Cl. 209-81) This invention relates generally to improvementsin the field of automatic inspection machinery for ascertaining theaccuracy of certain dimensions of bottles, jars, and other containersmade from dielectric materials.

The general object of this invention is to provide a fully automaticapparatus for positioning, inspecting, and segregating bottles, jars,and other articles according to their deviations of wall thickness froma predetermined standard. A more specific object of the presentinvention is to provide a mechanism that will automatically positionbottles, jars, and other like articles for electrical inspection.

Another object of the present inventionis to provide a rapid, accurate,convenient, and dependable electrical system for checking the wallthickness of bottles, jars and other like articles made from dielectricmaterials. A further object of the present invention is to provide anelectrically operated system for automatically rejecting articles thatare defective, as determined by the beforementioned electricalinspection system.

A variety of methods are known and being used by the manufacturers andpackers of bottles and jars to detect defects in the wall structure ofsuch articles. These methods comprise visual inspection, mechanicalgauging of the wall with calipers or like instruments, and testing ofthe containers by impact means. These inspection methods are expensive,time consuming, and relatively inaccurate and are subject to thepersonal variations of the persons making such inspections.

Bottles and jars made by glassware forming machines often have defects,such as excessively thick and excessively thin side wall portions,resulting from uneven blowing operations, poor temperature distributionin the glass gobs, uneven initial contact of the gobs with the walls ofthe parison molds, or other malfunctioning of the feeding and formingequipment. By the use of the present invention, these defects can beautomatically ascertained and the defective ware automatically rejectedwithout the supervision or attention of any person. The method ofoperation and the attendant advantages of this inven tion will beapparent from the following description of the preferred embodimentwhich is disclosed with reference to the following drawings, in which:

Fig. 1 is the top plan view of the assembled machine showing bottlesbeing fed in at one side thereof and acceptable bottles being dischargedtherefrom;

Fig. 2 is a view of section 2-2 of Fig. 1, showing the driving membersand certain of the related parts thereof, certain elements of' thecomplete apparatus being omitted and other elements being rotated out oftheir true locations to afford a better view of the parts shown;

Fig. 3 is a plan view of a section of part of the machine on line 3--3,Fig. 2, showing in relatively large proportion the cooperative drivingmembers, the drive for the rejection mechanism, and certain drivenmembers;

Fig. 4 is an enlarged perspective view of the rejection mechanism andalso shows the interacting members that separate the defective orrejected bottles from the acceptable bottles;

Fig. 5 is a partial view of section 55 of Fig. 1, showing the details ofthe construction of one of the two electrical inspection heads;

Fig. 6 is a partial view of section G-6 of Fig. 1,

showing the details of construction of the other electrical inspectionhead; and

Fig. '7 is a schematic drawing of the electrical system of the machine.

Generally speaking, the method of operation 26 of this machine is tofeed bottles individually from a succession of bottles into a rotatingcarrier which carries each bottle in its turn to a position in front ofeach of two inspection heads, at which time each inspection head ismoved adjacent to each bottle to perform the inspection operation. Whileopposite each inspection head, the individual bottle is rotated aboutits axis, which is held vertical. The ascertainment of excessivedeviations of the wall thickness of a bottle being inspected causes anelectrical impulse which is transmitted to an electrical system whichoperates a mechanism to automatically reject the defective bottle at alater time. Acceptable bottles that meet the dimensional requirements asto wall thickness are discharged periodically at one side of themachine.

The specific manner in which the above generally described operationsare accomplished can be understood from the following description of thedetails shown in the accompanying drawings.

Referring first to Fig. 2, all the driving members are enclosed within ahousing which is generally designated I. A driving motor 2 suppliescontinuous and uninterrupted rotation of a worm 3 which is engaged witha worm gear or wheel 4. Worm gear 4 is fixed to a vertical shaft 5 whichis suitably supported in antifrictlon bearings 6 and 1. Fixed to shaft 5is a Geneva driving hub 8 carrying a driving roller 9. A Geneva wheelIII is fastened to a vertical indexing shaft II and is suitably locatedin cooperative relationship with roller 9 and driving hub 8 in themanner usual in conventional Geneva drives. Eight radial guide slots l2(Fig. 3), having parallel sides, are formed in Geneva wheel H3. Theinteraction between the driving roller 9 and the guide slots indexesshaft periodically to eight different positions per revolution of theshaft about its axis. A slot |3 is formed in one side of shaft 5 (Fig.2) to permit passage of the periphery of Geneva wheel l during theindexing motion of the wheel. A shoulder M is formed on thecircumference of shaft and is positioned so as to engage semicylindricalrecesses l5 (Fig. 3) in Geneva wheel l0 and thereby to hold wheel ID inposition between indexing movements. The upper extremity of shaft 5carries a double sprocket |6 engaging roller chains l1 and I8. Asprocket I9 is driven by chain H, the sprocket being mounted on avertical shaft 29 which is suitably supported by bearings in housings 2|and 22 (Fig. 2). Shaft 20 is continuously rotated at the same rotationalspeed at which shaft 5 is rotated by motor 2. The rotation of shaft 20at a speed equal to that of shaft 5 is accomplished by making the pitchdiameter of sprocket |9 equal to the pitch diameter of the sprocket l6.Stationary, horizontal support plates 23 and 24 hold bearing housings 2|and 22, respectively, in proper spaced vertical relationship.

Chain |8 drives a sprocket 25 (Fig. 3), the chain engaging with an idlersprocket 26. A sprocket 27 (Fig. 3) which is fastened to a vertical feedshaft 28 also is driven by chain l8. Sprocket 25 has a pitch diameterequal to that of driving sprocket l6, sprocket 25 thereby having arotational speed equal to that of sprocket l6.

Main support members 29 (Figs. 1 and 3) may be provided between thestationary support plates 23 and 24, Fig. 2.

Fixed to vertical indexing shaft I I, Fig. 2, is a carrier disc 3|], thefunction of which will be described hereinafter. Attached to shaft II isa carrier, generally designated 3|, formed of. a central support member32 and two horizontal, annular, flat flanges 33. Carried between flanges33 are eight positioning assemblies, generally designated 34. Eachassembly consists of vertical shaft members 35 and 35a suitably mountedin antifriction bearings 33a. Mounted on a tube 35b fixed to members 35and 35a are two vertically spaced discs 36 made from Micarta or otherdielectric material. Each disc 36 carries a soft rubber tire 31 on itsperipheral surface. Disposed in the space between discs 36 is a flatannular insulating positioning plate 39 attached to central supportmember 32. A series of eight rectangular notches or recesses 39a areequally spaced about the periphery of plate 39, each notch beingcentrally disposed between the adjacent two positioning assemblies (seeFig. 1). A roller 38 is attached to the upper extremity of shaft 350.Each positioning assembly is free to rotate in its bearings.

The cooperative action among notches 39a,

positioning plate 39, and the positioning ,assemblies 34 is to retainthe bottles in the proper angular position and to move them to theinspection positions. The rotation of the bottles when in the inspectionposition will be described hereinafter.

The upper extremity of shaft 20 carries a sprocket 40 which is pinned toshaft 20 and rotates continuously therewith. A roller chain 4| engagessprocket 40 and cam actuating sprockets 42 and 42a (Fig. 1). Chain 4|also engages a rotation sprocket 43 and an adjustable idler sprocket 44which is used for adjusting'the tension and taking up the slack of chain4|. Rotation sprocket 43 is pinned to a short vertical shaft 45 whichhas permanently attached to it an article rotation wheel 46 bearing arubber tire 4! on its peripheral surface (Fig. 2). Shaft 45 is suitablypositioned in bearings to bear a cooperative relationship to eachpositioning assembly 34 as it is indexed into operating positionintermediately between the two inspection heads (Fig. 1). As eachassembly is indexed into operating position by virtue of the beforedescribed Geneva motion, the periphery of roller 38 on the shaft 35a ofthat assembly comes into bearing contact with tire 41 of wheel 46. Wheneach positioning assembly is so positioned, the rotation of shaft 20 istransmitted to vertical shaft 45 which, in turn, rotates the positioningassembly by means of the friction drive of rubber tire 41.

The cam actuating sprocket 42 is permanently attached to a vertical camshaft 48, attached to the lower end of which is a cam 49 bearing inguiding relationship on a cam roller 50 (Fig. 5). Cam roller 50 ispinned by pin 5| to inspection head or housing 52. Housing 52 is guidedfor radial motion outwardly and inwardly from the center of indexingshaft II by parallel guides 53. A spring 54 bears on housing 52 andkeeps roller 50 bearing in guiding contact on the lateral surface of cam49. Bearing plates 55 and 56 (Fig. 5) are fixed to the housing 52 andcarry antifriction bearings 55a and 56a, respectively, to suitablysupport a shaft 51. Attached to the shaft 51 are two insulating discs 58in vertically spaced relationship. Spaced vertically between discs 58are two capacitor pick up plates 59, mounted in insulating bushings 60.The bushings are, in turn, mounted in inspection head 52. Spaced abovethe upper Micarta disc 58 is an additional capacitor pick up plate 59ain an insulating bushing 60a. Side surface 6| of inspection head 52 isformed to define a contour which approximates in shape the outsidecontour of a bottle 62 being inspected. Capacitor pick up plates 59 and59a are mounted flush with surface 6|. Bottle 62 is held in spacedrelationship to the capacitor pick up plates by the peripheral surfacesof Micarta discs 58. A steel post 63 is attached to lower flange 33directly below each rectangular notch 39a in the periphery of member 39.Each steel post has a steel bearing pin 64 inserted in it to provide abearing contact of small area for the bottom surface of the bottle torest upon while it is being indexedby carrier 3|. A positioning roller65, carrying rubber tire 66, is

spaced vertically above pin 64 to maintain bottle 62 in contact with pin64 and to permit rotation of the bottle about its axis. A retaining wall66a. (Fig. 1) is formed along part of the arc of action defined bymovement of carrier 3| to prevent bottles from toppling outwardly off ofpins 64 when the bottles are being indexed to and from the inspectionheads.

The second inspection head 61 (Fig. 6) is constructed in a mannersimilar to that of 52 and is guided in its radial motion by cam 68(Fig. 1) Cam 68 is driven by cam sprocket 42a in a manner identical tothat hereinbefore described with reference to inspection head 52. TwoMicarta discs 69 are vertically spaced and separate three capacitor pickup plates 18. The combined effeet of capacitor plates 10, 59 and 59a isto sweep a major portion of the side wall surface of the bottle beingtested during a cycle of relative rotation about the vertical axis ofthe bottle, as will be described hereinafter.

Inspection heads 52 and 61 are angularly positioned So that there willbe a bottle at each inspection head after each indexing movement of thebottle carrier. A positioning assembly 34 then will be intermediatelyspaced between the inspection heads with roller 38 of the positioningassembly in driven contact with the rubbertired wheel 46, as shown inFig. 2. As the central carrier 3| is periodically indexed by the actionof Geneva wheel I0, a new bottle will be brought into position to beinspected by inspection head 61, and the bottle that was previously atinspection head 61 will be shifted to the inspection position in frontof inspection head 52. Correspondingly, a different positioning assembly34 will be brought into bearing contact with the rubber tire 41 ofarticle rotator wheel 46. Through this action, the bottles beinginspected will suecessively be passed to and inspected by eachinspection head and each will be rotated for complete inspection of theperipheral wall of its body by means of the rotation of the positioningassemblies 34 as driven by shaft 45 and its associated parts. In timedrelationship, earns 49 and 68 will guide inspection heads 52 and 61,respectively, so that the inspection heads will approach and recede fromthe bottlesbeing inspected in proper timed sequence.

Main capacitor plate 1| is of substantial vertical extent and is formedarcuately adjacent to the periphery of carrier 3| and is supported by aplurality of insulating mounts 1Ia. The vertical extent of this maincapacitor plate exceeds the height of the bottle being inspected by anamount suflicient to insure a uniform field distribution. This maincapacitor plate extends arcuately on both sides of the inspection headsand has openings or slots 1Ib and H0, respectively, opposite inspectionheads 61 and 52 to permit their passage therethrough in the course ofthe radial movements of such heads; The main capacitor plate suppliesthe electrostatic field which is distorted by the passage therethroughof the dielectric material of the bottle being tested. The distortion ofthis field by the presence of the dielectric material of the bottlechanges the capacitance between each capacitor pick up plate and themain capacitor plate. Insulating discs 58 and 69 act primarily aspositioning rollers. Micarta or other suitable insulating material isused to minimize or obviate any extraneous attendant distortion of theelectrostatic field produced by the main capacitor plate. The metalwalls of the inspection heads provide shielding for the capacitor pickup plates.

Associated with the inspection heads 52 and 51 are solenoids 12 and 13,respectively (Fig. 3). These solenoids are of conventional type thatwill draw a central movable member within the coil thereof when the coilis energized by an electrical current of suitable magnitude. Connectedto the ends of the movable members of the solenoids are ends of bellcranks 14 and 14a. These bell cranks are pivoted on stationary,permanently mounted, vertical pins 15 and 15a, respectively. The otherend of each bell crank is disposed in working relationship to the outerends of rejection pins 16 which are eight in number (Figs. 2 and 3).These rejection pins are equally spaced and are mounted angularly in therim portion 11 of the carrier .disc 30 (Fig. 2).

Located in disc 30 above each rejection pin is a spring 18 held in placeby a tapered, threaded plug 19. The spring is compressed so as to bearon the plug and on the surface of the rejection pin so as to provide adrag which will resist the motion of the rejection pin in meinber 30.-Transversely mounted in the outer end of each re jection pin is a limitpin and transversely mounted on the inner end of each rejection pin is alimit pin ill. The sole function of limit pins 80 and BI is to restrictthe extent of radial motion inwardly and outwardly, respectively, ofrejection pin 16 in rim 11 of carrier disc 30.

When a bottle whose wall thickness is above or below the predeterminedstandard is rotated in the electrostatic field produced by the maincapacitor plate, the inspection head'which detects this deviationtransmits an impulse to a hereinafter described electronic circuitwhich, in turn, energizes the sclenoid which is electrically associatedwith the inspection head. The energizing of the solenoid causes thecentral. movable member to move inwardly, thereby rotating bell crank 14(or 14a) on its pivot pin 15 (or 15a) and swinging the opposite end ofthe bell crank, thereby forcing rejection pin 16, which corresponds inits angular location to the defective bottle being inspected, inwardlyto the limit permitted by limit pin 80. The inwardly displaced rejectionpin will be correspondingly indexed in its angular location along withthe defective bottle until the inner end of the rejection pin comes intobearing contact with a rejection cam 82 which is permanently mounted ona lever 83 (Fig. 4). Lever 83 is intermediately pivoted about ahorizontal pivot pin 84. A clevis 85 is pivotally attached to the end oflever 83 by a pin 86. A vertical push rod 81 is carried by the clevis 85and may be locked thereto by nut 88. Push rod 81 is guided for verticalmovement by the stationary support plate 23 and a suitably disposedstationary bracket 89 which is secured to support plate 23. Latch 90 ispivoted about a horizontal pin 9I and rests on the upper end of push rod81. The action of latch 90 will be described presently. Sprocket 25which is driven with continuous rotation by roller chain I8 is mountedon a vertical shaft 92. A vertical pin 93 is attached to block 92a andis eccentrically located relative to axis of shaft 92. Block 92a may bemade integrally with shaft 92 or may be an independent unit securedthereto. A link 94 is connected-to block 92a by pin 93 and is connectedby a vertical pin 95 to a lever 96 which is attached to the lower end ofvertical shaft 91. Acceptance lever 98 is secured to shaft 91 by meansof a set screw 98a.- A projection 99 from one side of the acceptancelever has mutually perpendicular guiding faces I00 and I00a,respectively, which guide the movement of latch 90. A second projection[M is provided on the side of acceptance lever 98. Pivot pin 9| ispermanently secured in projection |0I and extends laterally therefrom tosupport in swingable disposition latch 90. A rejection lever I02 ispivotally mounted on shaft 91 but is not attached thereto. Rejectionlever I02 has a projection I03 therefrom and a latch plate or pawl I04permanently mounted thereon. The lower end of latch plate I04 projectsdownward in cooperative relationship with face I05 of latch 90. Face I05is brought into working disposition with the lower end of plate I04 whenthe latch 90 is raised by push rod 81. The end portion of rejectionlever I02 has an open-ended groove I06 in its lower surface into whichthe upper end or neck portion of each bottle is moved as such bottlenears a reject station during its travel about the center line ofindexing shaft II. A tension spring I01 holds rejection lever I02against stop I08. As acceptable bottles are indexed about the centerline of shaft II, the neck portions pass through groove I06 and are thenindexed to correspond in location to the entrance of acceptance chute B(shown in Fig. 1). Periodically, acceptance lever 98 pivots about shaft91 under the action of crank 96 and link 94 and positions the acceptablebottle I09 between guide bars IIO onto the bottom surface I II of theacceptance chute, Fig. 4. The acceptance chute B conveys the acceptablebottles to a moving conveyor or other suitable means (not shown) forconveying the bottles to a filling machine or other destination. If adefective bottle should come before inspection heads 52 and 61,rejection pin 16, which corresponds in angular position to the defectivebottle, will be forced inwardly as has been described heretofore. As thedefective bottle continues to be indexed, its corresponding rejectionpin 16 will come into bearing contact with cam 82 thereby pivoting lever83, which, in turn, raises push rod 81 thereby raising latch 90 andbringing surface I into working relationship with latch plate I04.During the next periodic oscillation of shaft 91, face I05 will comeinto bearing contact with the extension of latch plate I04 and willthereby rotate rejection lever I02, overcoming the force of spring I01.This sequence of actions will cause rejection arm I02 to swingoutwardly, thereby throwing the defective bottle outwardly from themachine to fall into a cullet bin or other suitable container. It is tobe noted that the rejection arm discards defective bottles from theindexed position immediately prior to and adjacent to the entrance tothe acceptance chute.

After the rejection of the defective bottle, the rejection pin 16 runsover the end of cam 82. The weight of push rod 81 and clevis 85 causeslever 83 to rotate on its pivot pin 84, thereby lowering push rod 61 andreleasing face I05 of latch 90 from its engaging relationship with theend of plate I04. The tension spring I01 will thereafter returnrejection arm I02 to its inactive position bearing against stop I08. Theinwardly displaced rejection pin 16 will continue to be indexed aboutthe center of shaft II until the innermost end thereof comes intobearing contact with a stationary cam track II2 (Fig. 3) which isstationarily mounted within the rim portion of disc 30. As pin 16 slidesalong the face of cam track II2, the pin is gradually returned to itsoriginal outwardly extending position, The pin is now in position to gothrough the same cycle over again and to reject or permit acceptance ofanother bottle which is fed into the machine at the correspondingangular position from entrance chute A (Fig. l). The bottles are fedinto the machine from chute A by means of driving lugs I I3 which aremounted on feed chain II4 (Fig. 1). This feed chain is drivencontinuously and at the proper relative speed by feed shaft 28 which isrotated by the continuously moving chain I8.

The electronic system which acts cooperatively with the mechanicalsystem to separate the de fective from the acceptable bottles is shownschematically in Fig. 7, conventional parts being showndiagrammatically. Referring to Fig. 7, a high frequency voltagegenerator II5 energizes the main capacitor plate H at a suitablefrequency. For the particular embodiment disclosed, a value ofapproximately three megacycles per second is suflicient. An impedancematching network I I6 matches the impedance of condenser plate H withthe line 511 so that energy can be transmitted through the system with amini mum of losses. An alternating potential of approximately 400 voltsmaximum value preferably is created at plate 1I although it is possibleto use a wide range of voltages satisfactorily. A pickup plate 10 (orany one of pickup plates 59 or 59a) is connected to a second impedancematching network I I1 which in turn is connected to a pickup voltagecoil II8, one side of the coil being grounded. Impedance matchingnetwork 1 facilitates transmission of energy from pickup plate 10 topickup coil I I8 with a minimum of losses in a similar fashion to thatof impedance network II6. A high frequency voltage of approximatelythree megacycles per second is transmitted from the high frequencygenerator II5 to an attenuator II9, the function of which will bedescribed presently. Connected to the attenuator is a phase shiftingnetwork I 20 which is connected to an injection voltage coil I2 I.Injection voltage coil I2I and pickup coil II8 form part of a mixing andcoupling transformer I22.

Attenuator II9 makes it possible to control the amplitude of theinjection voltage going from the high frequency voltage generator tocoil I2I. The phase shifting network I20 permits shifting of the phaseangle of the high frequency voltage relative to the time reference axis.A second coil I22a of the mixing and coupling transformer is connectedto a variable gain voltage amplifier I23. The amplifier, in turn, isconnected to a discriminator and rectifier I24. Connected to therectifier is a thyratron I25 which controls the flow of current to relayI26 which, in turn, controls the flow of line current to thebeforementioned rejection solenoid 13 (or 12). An indicator on recordingmeter I21 may be connected, if desired, to the circuit of rectifier I24.

The operation of the circuit is as follows. High frequency voltagegenerator II5 feeds through the impedance matching network I I6 toproduce an alternating high frequency potential on plate 1I. Plate H andpickup plate 10 form a capacitor, the capacitance of which varies withthe dielectric constant and the thickness of the material imposed in theelectrostatic field between plates H and 10. Plate 1I produces anelectrostatic field in space in the usual well-known manner. Theelectrostatic lines of force in space tend to repulse one another andturn towards the concentrated area of pickup plate 10. For this reason,the pickup plates should be spaced at the same distance from eachportion of the adjacent main capacitor plate. The capacitor actionbetween plates 10 and H produce an alternating high frequency voltage inplate 10 which is proportionately increased as materials, having higherdielectric constants or having largercross-sectional areas forconcentration of the lines of force, are interposed between the plates.The potential of plate 10 is fed through impedance matching network II1to pickup voltage coil I I8. An alternating potential of the samefrequency as that in coil I I8 and having equal amplitude but havingshift in phase angle can be produced in coil I2I by means of theattenuator I I9 and the phase shifting network I20, respectively. Whenthe circuit is so adjusted, no voltage will be induced in coil I22a ofthe mixing and coupling transformer I22.

Control of the amplitude and phase of the potential of coil I2I is usedto produce the zero or reference setting of the electrical system. Thus,a bottle of the mean preferred wall thickness is placed in theinspection position before plate III; the amplitude and phase angle ofthe potential being fed into coil I2I are adjusted by attenuator H9 andphase shiftin network I20, respectively, until no potential is inducedin coil I22a. When adjusted as described, the circuit will be unbalancedby anything that tends to increase or decrease the capacitance of thecapacitor formed by plates 10 and II. Thus, if a bottle having a wallthickness in excess of the mean preferred thickness is placed inposition before the pickup I0, capacitance of the aforementionedcapacitor will be increased and a higher voltage will be produced onplate I0. Conversely, a bottle having a wall thickness less than themean preferred thickness will decrease the capacitance of the capacitorand will produce a correspondingly lower potential in plate 10. Ifbottle 62 is removed altogether from the field produced by plate II,there will be a drastic drop in the voltage of plate I0, since thedielectric constant for air is 1.00, whereas the dielectric constant forglass is approximately to 9.

Any of the before-described variations of the capacitor, formed byplates I0 and II, different from the conditions existing when a bottleof the mean preferred thickness is in position before plate I0 willproduce an unbalance between coils I I8 and I2I and will thereby inducea voltage in coil I22a. The induced voltage under normal conditions willnot be of sufficient magnitude to operate ordinary indicating andrejection circuits. Therefore, the induced voltage is amplified inmagnitude by voltage amplifier I23. The amplified voltage is fed into afull wave rectifier which, in turn, provides a proportionate directpotential to the grid of thyratron I25. The thyratron circuit isadjusted so that an unbalance in the mixing and coupling transformer I22in excess of a certain magnitude will fire the thyratron and permit flowof current to relay I26. When relay I26 closes, alternating line currentis fed to rejection solenoid I3 (or 12) which, in turn, sets rejectionpin I6 in the manner hereinbefore described.

For a quantitative evalution of the magnitude of deviations in the wallthicknesses of the bottle being measured, an indicator of any suitabletype may be connected to the rectifier as shown in I21.

Once the thyratron tube has fired, it will permit a continuous flow ofcurrent until reset. The

resetting of thyratron I25 is accomplished by a micro-switch I28 whichis mounted on stationary support plate 23 (Figs. 1 and 2) and which isactuated by the radial movement inwardly and outwardly of inspectionhead 61 (or 52). As the inspection head is forced outwardly by cam 68after the inspection operation, the normally closed micro-switch I28will be opened and the flow of current to the plate of the thyratronwill be interrupted. The operation of the microswitch in response tomovements of the inspection head accomplishes a dual purpose; namely, itresets thyratron I25 after each rejection impulse and also prevents afalse operation of the thyratron tube during the period when a bottle isnot present before the pickup plate but is being indexed to position bythe indexing apparatus.

The interruption of the current from the thye ratron tube to the relaybreaks the circuit to the rejection solenoid 13 (or 12). As soon assole- 10 noid I3 is de-energized, bell crank 14 (or 14a) swings to itsneutral position under the action of tension spring I29 (or I29a), Fig.3.

Thus, in general terms, the operation of the electrical system is suchthat, when properly adjusted, any variation of the capacitance of thecapacitor, formed by plates I0 and 'II, from the capacitance that it haswhen a bottle of the mean preferred wall thickness is in inspectionposition causes an unbalance in the electrical system. The unbalance isused to fire a thyratron which, in turn, controls a relay feedingcurrent to a rejection solenoid. The sensitivity of this system can becontrolled by changing the degree of amplification in the voltageamplifier of the unbalance produced in the mixing transformer. Thisfactor can be utilized to permit the passage of bottles through theinspection machine without rejection even though the bottles have acertain predetermined degree of varation from the mean preferred wallthickness.

It is recognized that the edge effects of plate II introduce a certaindegree of error in the operation of this system. However, these effectshave been found to be negligible. Because of the relatively small areaof pickup plate 10, the effect of this system is to measure a localizedregion in the bottle wall immediately in front of the pickup plate Ill.

Only one voltage generator H5 and one impedance matching network IIB arerequired to energize main capacitor plate II. The three pickup plates ofeach inspection head can be used to operate one rejection solenoid. Theremainder of the described electronic system must be supplied for eachpickup plate of both inspection heads.

A series of experiments with the before-mentioned electrical ystem hasshown that for the disclosed geometry of the capacitor plates, theoptimum air gap between the external wall surface of the bottle and theface of the capacitor pickup plate is approximately one-eighth of aninch. With this air gap spacing, the maximum capacitance will resultfrom a given bottle, and the functioning of the electrical system willbe relatively insensitive to small deviations of the bottle from theproper inspection position.

The experiments have further shown that pickup plates having diametersranging from oneeighth inch to an inch are satisfactory for theoperation described. The diametral clearance between the pickup platesand the shielding wall structure of the inspection head has been held toone-sixteenth to one-eighth of an inch with satisfactory results. Pickupplates and associated parts of dimensions and configurations other thanthose shown and described herein may be used. However, havingestablished fixed dimensions for any factors influencing the capacitanceof the capacitor system, the other dimensions of the system should beara definite relationship to the fixed dimensions for best results.

In review and summary, the general operation of the machine is asfollows. A continuous stream of bottles to be inspected may be suppliedto chute A. Driving lugs II3 on chain II4 periodically feed the bottlesindividually into the inspection machine. Each bottle is forced inwardlytowards the center of the machine until it resides in a rectangularnotch or recess 39a of plate 39 and rests against tires 31 of discs 36of positioning assemblies 34. Each bottle is indexed periodically bymovement of its carrier until it comes to the first inspection head 6111 at which position the inspection head moves inwardly into inspectingposition. The bottle is rotated by means of tire 41 and a positioningassembly adjacent to the bottle. As the bottle rotates in front of theinspection head, it is held in spaced relationship therewith by discs69. Condenser pickup plates I sweep a limited annular region around thecircumference of the bottle. The inspection head then moves outwardlyunder the action of cam 68 and the bottle is indexed to the secondrejection head 52 which, in turn, moves inwardly into inspectionposition under the guidance of cam 49. Again the bottle is rotated aboutits axis by means of the positioning assembly which is in workingdisposition to tire 41 of wheel 46. Capacitor pickup plates 59 and 59asweep a different alternate circumferential region of the bottle notcovered by the capacitor pickup plates of the first inspection head. Ifthe bottle is within permissible tolerances of wall thickness, it willcontinue to be indexed about shaft II, the neck portion of the bottleeventually engaging in the groove I06 of rejection lever I02. The bottleneck will completely pass through groove I06 and come into positionbefore guide bars I I0. At that time, acceptance arm 98 will move inproper time sequence to gently push the acceptable bottle 01! of itssteel bearing pin 64 onto the surface of the acceptance chute B. If adefective bottle with a wall thickness not within the permissibletolerances should come before the inspection head 52 or 61, it willeffect the capacitance of main capacitor plate and the capacitor pickupplates so as to activate the electronic circuit and energize either orboth solenoids 12 or I3. Bell crank 14 (and/or 14a) will thereby beswung about pivot pin 15 (and/or 15a) and force the correspondingrejection pin I6 inwardly. The rejection pin I6 will bear a certainangular relationship to the defective bottle and will retain thatangular relationship until the bottle is rejected. The inwardlydisplaced rejection pin 16 engages with rejection cam 82, therebyraising push rod 81 and engaging face I of do 90 with the latch plateI04 of the rejection lever I02. On the next periodical oscillation ofacceptance arm 98 under the action of eccentric pin 93, face I05 willcome into bearing contact with the lower end of latch I04, therebyrejecting the defective bottle by swinging arm I02 outwardly from thecenter of the machine. The inwardly displaced rejection pin is properlyspaced angularly so that rejection arm I02 swings outwardly at the timethe neck portion of the defective bottle is en aged in slot I06. Thedefective bottle having been rejected, inwardly displaced rejection pinI6 rides over the end of rejection cam 02 permitting push rod 81 andlatch 90 to lower under their own weights, thereby permitting the returnof the rejection lever I02 to its inactive position against stop I08under the action of spring I01. Inwardly displaced rejection pin I6 willcontinue to be indexed about the center of shaft II until it is returnedto its outermost position by hearing against the surface of cam tractII2.

If a rejection pin I6 is not displaced inwardly by the solenoid 12 or13, it will completely bypass rejection cam 82 and will not impart anyaction to the rejection mechanism.

It is to be noted that the units of the electrical system should be wellshielded and that coaxial cables should be used as indicatedsymbolically inFig. 7.

ments of this invention will be apparent to those skilled in the artafter reading the foregoing disclosure. It is desired that the presentspecifications be construed as broadly as possible in light of the priorart to encompass such modifications within the spirit and scope of theappended claims.

I claim:

1. In combination, a main capacitor plate having an aperture therein, aninspection head formed to pass through said aperture into inspectingposition adjacent to an inspection station for a jar, bottle, or likearticle, means for conveying successive articles to and away from saidinspection station, a plurality of spaced capacitor pickup platesmounted on, insulated from, and shielded by said inspection head, meansto position said inspection head in said inspecting position relative tosaid article, electrical means associated with said main capacitor plateto establish a high frequency electrostatic field through the wall ofsaid article, tuned electrical means associated with said pickup platesresponsive to changes of mutual capacitance between said pickup platesand said main plate caused by variation of wall thickness of saidarticle from a predetermined standard, and normally inactive rejectionmeans activated by said second electrical system to separate defectivearticles from acceptable articles.

2. In combination, an arcuate main capacitor plate having an aperturetherein, an inspection head having a face contoured to simulate theexternal shape of an article bein inspected and formed to pass throughsaid aperture of said main plate to an inspecting position relative toan inspection station, means for conveying successive articles to andaway from said inspection station, a plurality of spaced pickup platesmounted on, insulated from, and shielded by said inspection head andcentrally located within said aperture flush with said contoured face,means to position said inspection head at its inspecting positionrelative to an article at the inspection station, electrical meansassociated with said main capacitor plate to establish a high frequencyelectrostatic field through the wall of said article, tuned electricalmeans associated with said pickup plates responsive to changes of mutualcapacitance between said pickup plates and said main plate caused byvariations of wall thickness of said article from a predeterminedstandard, and normally inactive rejection means activated by saidelectrical system to separate defective articles from acceptablearticles.

3. In combination, a plurality of inspection heads, each havin one faceformed to simulate the contour of an article being inspected, aplurality of recesses vertically spaced in said contoured face of eachinspection head, a plurality of shielded and insulated capacitor pickupplatesmounted in said recesses flush with said contoured face andlocated so as to sweep a major portion of the wall of said articleduring rotation of said article before said inspection heads, a maincapacitor plate arcuately formed between the contoured faces of theinspection heads and having apertures for said inspection heads to passthrough, means for presenting and rotating said article in turn beforeeach inspection head, means for maintaining said article in spacedrelationship with said inspection heads, electrical means associatedwith said main capacitor plate and said pickup plates to provide anelectrostatic Many modifications and alterations of the ele- 76 fieldtherebetween, electrical means responsive to changes in capacitance ofsaid main plate and pickup plates caused by variations in wall thicknessof said article from a predetermined standard, normally inactiverejection means activated by said second named electrical means toseparate defective from acceptable articles.

4. Apparatus as defined in claim 3 wherein said pickup plates arecircular in configuration and between one-eighth inch and one inch indiameter and are spaced radially from said inspection head byone-thirty-second to one-sixteenth of an inch.

5. In an apparatus for automatically detecting and rejecting jars,bottles, and like articles having excessive variations of wallthickness, a carrier mounted for intermittent indexin about a verticalaxis, said carrier having a plurality of angularly spaced notches aroundthe periphery thereof, a plurality of positioning roller assembliesangularly disposed adjacent to said notches, support pins located onsaid carriercorresponding in position to said notches, said positioningassemblies, notches and support pins being formed to retain saidarticles for indexing about said axis, a plurality of inspection heads,a plurality of cam mechanisms to move said inspection heads radiallyinwardly and outwardly from said carrier to bring said headsperiodically into inspectin position adjacent to said articles, meansassociated with said positioning assemblies to rotate said articlesabout the axis of the latter when in inspection position before eachinspection head, means for holding saidv inspection heads in spacedrelationship to said articles during inspection, electrical meansresponsive to variations of wall thickness of said articles detected bysaid inspection heads, normally inoperative rejection means associatedwith said electrical means to reject articles ascertained to bedefective by said inspection heads, microswitches operated by the radialmovements of said inspection heads to prevent improper operation of saidrejection means during indexing of said article and to reset theelectrical means after each rejection cycle, and continuously op- 45crating acceptance meansto eject acceptable arplurality of recessesspaced in said contoured face of said inspection head, a plurality ofshielded and insulated capacitor pickup plates mounted in said recessesand located so as to sweep a major portion of the wall of said articleduring rotation of said article before said inspection head, a commonmain capacitor plate arcuately formed and located adjacent theinspection head outwardly of the outer contour of said article, meansfor presenting and rotating said article before said inspection head andsaid main plate, means for maintaining said article in spaced relationship with said inspection head and main plate, electrical meansassociated with said main plate and said pickup plates to provide anelectrostatic field therebetween, individual electrical means responsiveto changes in capacitance of each of said pickup plates with respect tosaid common main plate caused by variations from a predetermined wallthickness of said article contiguous to each respective pickup plate,and normally inactive rejection means activated by any of saidindividual electrical means to separate defective from acceptablearticles.

THEODORE C. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

